Confusion regarding recipe inconsistencies.

So DrinkSurfer posted this a while ago in the recipe section. The thing I've noticed is, he says final gravity is 1.024. However, Beersmith AND Hopville calculus have it much much lower - 1.013 and 1.008 respectively. What's with the huge discrepancy? Am I missing something?


Recipe Type: Extract
Yeast: Windsor
Yeast Starter: None
Additional Yeast or Yeast Starter: None
Batch Size (Gallons): 5
Original Gravity: 1.052
Final Gravity: 1.024
IBU: ~17
Boiling Time (Minutes): 60
Color: ~35 SRM
Primary Fermentation (# of Days & Temp): 11 @ 70
Tasting Notes: Nearly opaque with a creamy tan head. Subtly sweet, toasted malts come through, crisp

M.O. Stout (Milk Oatmeal Stout)

Light Dry Malt Extract – 4.5 lbs
Black Patent – 8 oz
Chocolate Malt – 12 oz
CARAPILS – 8 oz
Lactose – 1 lb
Oats, Flaked – 1 lb
Fuggle Pellet Hops – 1 oz (60 min)
Fuggle Pellet Hops - 1 oz (5 min)
Windsor Yeast
Irish Moss - 1 tsp

Steep oats for 15 minutes at 115 F.
Bring temp up to 155.
Steep grains and oats for 45 minutes.
Remove from heat.
Add malt extract.
Bring to boil.
Add bittering hops with 60 minutes remaining.
Add 1 tsp Irish Moss and 1 lb lactose at with 15 min remaining.
Add aroma hops with 5 minutes remaining.

Does the software recognize that lactose doesn't ferment? I think that will add .007 or so points. 1.024 is a pretty high fg.

Yea, removing one pound of lactose only lowers the FG by 2 points, so in hopville from 1.013-1.011. Maybe the posted recipe is completely off, or maybe beersmith and hopville have really high fermentability of lactose.

Unfortunately the recipe poster has been on in weeks.

hmm...There is only 4.5# of fermentable grain in the recipe so the 50% attenuation might be correct. I also see no reason to steep the flaked oats. Check some other sweet stout recipes in the recipe section and compare.

Jamil's calls for 7.2# of extract with 1# of lactose; OG 1.060, FG 1.023 for 6 gallons.

helibrewer said:

hmm...There is only 4.5# of fermentable grain in the recipe so the 50% attenuation might be correct. I also see no reason to steep the flaked oats. Check some other sweet stout recipes in the recipe section and compare.

Jamil's calls for 7.2# of extract with 1# of lactose; OG 1.060, FG 1.023 for 6 gallons.

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Interesting that both softwares show it with similar attenuation.

Steeping the oats is obviously a controversial subject, but haven't brewed that way in the past, I absolutely trust those they say that although it doesn't convert, it definitely adds mouthfeel.

I'm fascinated by this. If crafted this recipe from scratch in beersmith and was expecting 1.009 and got 1.024, it would be awful.

When I put this recipe into brewersassistant.com at 5.5 gallons it gives OG = 1.055, FG = 1.026 So I would say the other programs are not handling the lactose correctly.

helibrewer said:

When I put this recipe into brewersassistant.com at 5.5 gallons it gives OG = 1.055, FG = 1.026 So I would say the other programs are not handling the lactose correctly.

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Aha. Good find! How interesting and upsetting this is!!!

Heli- I just found a post on beersmith's forum where someone is asking the same exact question about Jamil's recipe you alluded to. It's been up for two months, been read 79 times, and never answered. This software is clearly REALLY off with it's expected fermentability of milk sugar - it seems like an easy fix.

J187 said:

Aha. Good find! How interesting and upsetting this is!!!

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Yes, I just created a recipe in BeerSmith using 100% lactose and it showed that the Lactose would fully ferment to an FG of 0.989....definitely a bug in BeerSmith!!!

I sent an email to beersmith, it will be interesting to hear what Brad says. I like the software a lot, but with that big of a discrepancy, you simply cannot even use it with regard to lactose in recipes.

From Brad Smith:

Hi,
This is a known bug that affects the FG estimation. It is high on my list of items to fix in the next build. Currently BeerSmith does not have a setting for "non-fermentable" grains.

OK, here's a guide to altering FG for unfermentables by adjusting yeast attenuation.

First calculate the percentage of gravity the unfermentables contribute to OG. Suppose you are adding 1 pound of lactose to make a 1.082 beer. Take the lactose out and see what your OG is now. Suppose that without the lactose, the beer would be 1.069, so the lactose would contribute 0.013 gravity points or 15.8% of the added gravity. Take 1 minus the 15.8% to get your attenuation adjustment, 84.2%. Now override your yeast attenuation by multiplying the default value for its attenuation by the adjustment factor.

I have a couple of batches where this formula has given me spot on FG, and the software has no trouble with OG.

Holy cow, I purchased brewing software because I love to brew and hate math! Think Id rather complain about about, and wait till the next release.

J187 said:

From Brad Smith:

Hi,
This is a known bug that affects the FG estimation. It is high on my list of items to fix in the next build. Currently BeerSmith does not have a setting for "non-fermentable" grains.

Click to expand...

I just stumbled across this issue, glad someone addressed it and that Brad is on top of it.